Endovascular catheter air block

ABSTRACT

This invention is an air block for industrial, medical, and non-medical uses. For example, the air block is connected to the proximal end of a vascular access catheter. The air block is either removably connected to the proximal end of the catheter or it is integral to the proximal end of the catheter. The air block permits introduction of other catheters or instrumentation through its central lumen and on into a lumen of the catheter while minimizing fluid loss or gain into the catheter. The air block further prevents air from entering the catheter and provides for removal of the air or other gas from the central lumen before it can enter the catheter where it could cause harm to the patient. The air block can be attached to various standard proximal catheter terminations including Luer fittings and hemostasis valve outer barrels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase filing under 35 U.S.C. §371of PCT/US2006/043149, filed Nov. 3, 2006, which designated the UnitedStates and was published in English, which claims priority to U.S.Provisional Patent Application No. 60/763,604, filed Jan. 30, 2006. Thecontents of these applications are incorporated herein by reference intheir entireties.

FIELD OF THE INVENTION

The invention relates to devices and methods for blocking gases forindustrial purposes such as during access to vessels, chambers, canalsor containers, or for medical purposes such as during access to thecardiovascular system or other body vessels or lumens, especiallyprocedures performed in the fields of cardiology, radiology,electrophysiology, and surgery.

BACKGROUND OF THE INVENTION

During certain interventional procedures that require vascular access,the patient is catheterized through a vein or artery and a catheter isrouted to the heart or other region of the cardiovascular system. Theinitial steps involve placement of a hollow tube within the bloodvessel. The hollow tube can be a sheath or catheter. In many cases,these catheters or sheaths are fairly long. Catheters or other devicesare routinely routed through these sheaths into the arterial side of thecirculatory system where pulsatile blood pressure generally averages 100mm Hg cycles and pulses at an average rate of approximately 1 to 3 beatsper second. The peak systolic pressures in the arterial side in a normalpatient are around 110 to 130 mm Hg and the lowest diastolic pressuresare around 70 to 90 mm Hg. In a hypertensive patient experiencing whatis known as high blood pressure, the peak systolic arterial pressure canexceed 250 mm Hg. A catheterization lab or operating room is typically aclean room, which is maintained at positive pressure ranging from 0 to 2mm Hg. When a catheter is routed into the arterial system, the distalend of a through lumen will be exposed to these arterial blood pressuresand a positive pressure gradient will exist between the distal end andthe proximal end of the catheter can be such that, unless properhemostasis is maintained, blood is forced out through the catheter intothe ambient environment.

There are an increasing number of cases where a sheath is routed to thevenous side. Its distal end is exposed to central venous blood pressure,which cycles at the same rate as the arterial side, approximately 1 to 3beats per second. The normal, healthy, pulsatile venous pressures arelower than those in the arterial side and can range between low valuesof around 3 to 5 mm Hg and peak values of around 15 to 20 mm Hg with anaverage of approximately 10 mm Hg. Patients with ectopic beats orpremature ventricular contractions can achieve nearly zero centralvenous pressure during part of the cardiac cycle. Patients withtricuspid incompetence and conduction pathologies can experience rightatrial pressures of −5 to −10 mm Hg. In the central venous circulation,for example, as measured in the right atrium of the heart, the distalend of the sheath can be exposed, during part or all of the cardiaccycle, to pressures equal to or below those to which the proximal end ofthe sheath is exposed. When the room or ambient pressure, to which theproximal end of the sheath is exposed, is above that of the distal endof the sheath, a negative pressure gradient or pressure drop can occur.Such a negative pressure drop allows air to be forced into the proximalend of the catheter. Should the air reach the distal end of the catheterby way of a through lumen, it could escape into the blood stream in theform of large or small bubbles, resulting an air embolism. Such airembolisms can cause harm to the health of the patient, or even death,and need to be avoided. This situation can be exacerbated by ambientroom pressures often found in the cath lab. Under normal conditions, theenvironment of the clean room, operating theatre, or catheterization labcan be maintained at an elevated air pressure of around 5 to 10 mm Hgabove exterior air pressure. Thus, a right atrial pressure, whichmomentarily dips to 2 mm Hg, can be overcome by a room air pressure of 2to 3 mm Hg causing air to be forced retrograde through the catheter andinto the circulatory system.

Typical arterial catheter procedures include percutaneous transluminalcoronary angioplasty, coronary stenting, aortic stent-graft procedures,endarterectomy, and the like. In the United States, more than 500,000 ofthese arterial procedures are performed each year. The number of venousprocedures being performed each year is increasing as more endovasculartherapies evolve or are developed for pathologies such as atrialfibrillation, mitral valve repair, mitral valve replacement, and thelike. There are currently more than 200,000 electrophysiology proceduresperformed in the right and left atrium of the heart annually in theUnited States. During a venous procedure, a catheter is routed throughthe venous circulation where low instantaneous, or pulsatile, pressurescan occur. During the approach to the heart and in preparation for atrans-septal puncture, the distal end of the catheter can reside in thevena cava or right atrium for a substantial amount of time. Suchpositioning renders the catheter at risk for being exposed to a negativepressure drop and the potentially catastrophic consequences ofretrograde air flow. An air embolism or bubble escaping into the venouscirculation can lodge in the lungs causing a pulmonary embolism.Pressures in the left atrium are similar to those in the right atrium.Left atrial pressure is pulsatile and can have peak values of around 10to 20 mm Hg and minimum values of between −5 and 5 mm Hg. Negativeminimum pressures are experienced in patients with certainpathophysiologies such as aortic stenosis. These types of patients areoften the ones who undergo catheterization procedures. Left sided(arterial) procedures, which are accessed from the right (or venous)side present a further complication in that a gas bubble or embolismthat escapes into the arterial side can be pumped by the heart tosensitive tissues where it can lodge, prevent distal blood flow, andthus cause ischemia. Such ischemia is potentially life threatening if itoccurs in the cerebrovasculature or the coronary arteries.

Current devices and methods prevent air entrainment into a sheath orcatheter or for preventing blood escape from these sheaths or cathetersinvolve the use of valves such as stopcocks, hemostasis valves,adjustable Tuohy-Borst valves, and the like. These devices are adequateat preventing the loss of substantial amounts of blood during arterialprocedures. The current devices, however, are less well suited topreventing air backflow into the sheath or catheter and possibly intothe patient. Instances can arise where a hemostasis valve breaks orbecomes disconnected from the sheath or catheter and a substantial bolusof air can enter the cardiovascular system with sometimes catastrophicconsequences. Even without such equipment failure, operator error canresult in air being pumped retrograde into the blood stream by ambientair pressure, if a Tuohy-Borst valve is not properly adjusted, ahemostasis valve becomes distorted, or too small a catheter is used forthe type of hemostasis valve.

There is a need for improved systems, devices, apparatus and methods forpreventing air entrainment into a patient through catheters routed intothe venous circulation. Such systems, devices, apparatus, and methodsneed to accept catheters or instrumentation through their central lumensand close the seal around those catheters better than current devices.The systems further need to close more quickly than the current systemswhen the inserted catheter is removed. The current systems need also tobe improved to prevent air passage retrograde back into the catheterwhile still maintaining device operability.

SUMMARY OF THE INVENTION

An embodiment of this invention allow work in a medical environmentwherein a pressure-differential is expected. Certain embodiments of theinvention will prevent air from entering and/or the escape of blood orother body fluids when a high pressure system (defined as aboveatmospheric) is accessed by interventional techniques.

For example, disclosed in one embodiment is an air block, or air trap,module that is affixed to the proximal end of a primary sheath, saidprimary sheath intended for vascular access. The module is generallydisposable and can be provided integral to the primary sheath,permanently attached to the primary sheath, or removably attached to theprimary sheath. The module permits introduction of catheters or otherinstrumentation through the central lumen of the primary sheath. In oneembodiment, the module further substantially prevents the loss of bloodwhen the distal end of the catheter is exposed to circulating blood,either in the arterial or venous system. The module traps substantiallyany air entrained into its interior lumen, prevents the air fromentering the through lumen of the primary catheter, and shunts the airout of the interior lumen of the module through an air exit port.

In other embodiments, the invention is applicable to industrial useswhere the blocking of gasses is desired. For example, an embodiment ofthe invention prevents gas from entering and/or the escape of gas ofother materials from a vessel when a high pressure system is accessed.

The air block comprises a main housing or shell, a catheter entry port,a catheter exit port, an inner channel further comprising perforationsin its wall, a fluid inlet port, and a gas, or air, exit port. Thecatheter entry port further comprises a hemostasis valve such as, butnot limited to, a slit valve, duckbill valve, Tuohy-Borst valve, or thelike. The catheter exit port further comprises a hemostasis valve suchas, but not limited to, a slit valve, a duckbill valve, a Tuohy-Borstvalve, or the like. The catheter exit port also comprises a dockingmechanism capable of securely affixing the air block to the proximal endof the primary sheath such that the catheter exit port and the inletport of the primary catheter are concentric and aligned.

In other embodiments directed to industrial or non-medical uses, thecatheter ports are replaced with a wide variety of different types ofports. Also, instead of a catheter, an embodiment of the invention canbe adapted to receive a variety of devices such as tubular devices forinsertion into containers, canals, vessels, passageways, or the like.Such devices can be designed, for example, to permit injection orwithdrawal of fluids or to keep a passage open. For example, anembodiment of the invention directed to industrial uses prevents gasfrom entering and/or the escape of gas of other materials from a vesselwhen a device is inserted into the vessel.

Thus, while certain embodiments are described with respect toendovascular uses or a catheter, the invention is not so limited and canbe configured for use in a variety of medical, non-medical andindustrial uses where the blocking of gas is desired.

The air block, or air removal system, can be operably connected to anexternal subsystem that provides a reservoir of liquid such as water,saline, Ringers solution, or the like pressurized to a level above thatof the venous pressure. The fluid delivery subsystem is operablyconnected to the fluid inlet port of the air block by way of a tube,manifold, or the like. The air block can also be operably connected toan external subsystem that withdraws or removes gas, specifically air,which can collect within the shell of the air block. The gas removalsubsystem is operably connected to the shell of the air block by the gasremoval port. Although the subsystems are referred to as being external,they can also be internal, integral to, or affixed to the air blockmodule. In an embodiment, the gas removal subsystem can comprise a gaspermeable membrane that permits gas such as air to pass butsubstantially prevents the loss of liquids such as water, saline, orblood. In this embodiment, a pump is operably connected to withdraw theair out of the trap through the as permeable membrane by generating apressure drop within a range that facilitates such air passage.

The air block, in an embodiment, can comprise one way valves at thefluid inlet port and at the gas outlet port. These one-way valves permitflow only in a single direction and make sure that fluid can only flowinto the air block from the fluid inlet port and that gas can only flowout of the gas outlet port. In another embodiment, the air blockcomprises an outer shell and a core tube, the core tube having either astraight tubular configuration or a central bulge directed radiallyoutward from the axis of the tube. The core tube can further compriseperforations large enough to cause gas collected within the core tube topass out into the surrounding area within the air block shell.

Another aspect of the invention is the method of use of the bubble, gas,or air block apparatus. The air block is affixed to the proximal end ofthe primary catheter, cannula, introducer, or sheath. The primarycatheter is flushed with saline and purged of air. The primary catheteris introduced into the vascular system, generally after first placing aguidewire, which is routed through the central lumen of the air block.The fluid inlet port of the air block is connected to a source of normalsaline. The gas outlet port of the air block can be connected to a fluidremoval system. The primary catheter is routed to its target location.The secondary catheter, or catheters, can be inserted through theproximal most hemostasis valve of the air block, through the centrallumen of the core tube of the air block, through the secondary air blockhemostasis valve, through the catheter lumen and into the vascularsystem at the target site. Any air that becomes entrained into the coretube of the air escapes through perforations in the core tube andmigrates into the larger diameter shell. The trapped air either remainswithin the larger diameter shell or it is drawn off by the fluid removalsystem either into the air or into an air reservoir. The fluid removalsystem can be optimized to selectively withdraw only gasses such as air.This selective withdrawal of air can be performed using a microporousmembrane fabricated from materials such as, but not limited to,polypropylene, polyethylene, polytetraflouoroethylene, other polyolefin,polyester, or the like. The membrane can have porous structures thatpenetrate from one side of the membrane to the other and with a size ofabout 100 microns with a range of 50 microns to 1000 microns. The poredensity and pore size can be selected to be compatible with a pressuredrop across the membrane, as generated by a pump or other suction(vacuum) or pressure generating device so as to remove a given volume ofair over a specified length of time without the loss of a substantialamount of liquid such as blood.

For purposes of summarizing the invention, certain aspects, advantagesand novel features of the invention are described herein. It is to beunderstood that not necessarily all such advantages may be achieved inaccordance with any particular embodiment of the invention. Thus, forexample, those skilled in the art will recognize that the invention maybe embodied or carried out in a manner that achieves one advantage orgroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein. These and other objectsand advantages of the present invention will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention. Throughout the drawings, reference numbers are re-used toindicate correspondence between referenced elements.

FIG. 1 illustrates a schematic view of the cardiovascular system of thehuman;

FIG. 2 illustrates a graph of the blood pressure within the arterialsystem at a location near the heart plotted against time;

FIG. 3 illustrates a graph of the blood pressure within the venoussystem in the region of the right atrium, plotted against time;

FIG. 4 illustrates a graph of the blood pressure within the left atriumof the heart, as it varies with time;

FIG. 5 illustrates a schematic diagram of an embodiment of the air blocksystem;

FIG. 6 illustrates an embodiment of the air block without subsystems orcatheters;

FIG. 7 illustrates an embodiment of the air block connected to a primarycatheter;

FIG. 8 illustrates an embodiment of the air block connected to a primarycatheter with fluid input and gas withdrawal subsystems attached;

FIG. 9 illustrates an embodiment of the air block connected to a primarycatheter with a secondary catheter inserted therethrough;

FIG. 10 illustrates a close up view of an embodiment of the air blockshowing a catheter inserted therethrough and a bolus of air being drawnout of the core tube into the lumen of the outer shell; and

FIG. 11 illustrates a side view of an embodiment of an air block or airblock that utilizes a dual chamber design.

FIG. 12 illustrates an embodiment of an air embolism prevention device.

FIG. 13 illustrates an embodiment of a system of preventing air embolismduring vascular procedures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with current terminology pertaining to medical devices,the proximal direction will be that direction on the device that isfurthest from the patient and closest to the user, while the distaldirection is that direction closest to the patient and furthest from theuser. These directions are applied along the longitudinal axis of thedevice, which is generally an axially elongate structure having one ormore lumens or channels extending through the proximal end to the distalend and running substantially the entire length of the device. Asdefined herein, a sheath is an axially elongate tube that can also betermed a catheter, a cannula, an introducer, or the like.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is therefore indicatedby the appended claims rather than the foregoing description. Allchanges that come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

FIG. 1 illustrates a schematic diagram of a part of the circulatorysystem 102 of a human 100. The circulatory system 102 comprises a heart112, an inferior vena cava 104, a superior vena cava 106, an iliac vein108, and a femoral vein 110. The heart 112 further comprises a leftventricle 114, a right ventricle 116, a left atrium 118, a right atrium120. The circulatory system 102 also comprises the aorta 122.

Referring to FIG. 1, all the functional components are operablyconnected to each other. The left ventricle 114 of the heart 112 pumpsblood into the aorta 122 by muscular contraction of the myocardium.Blood enters the left ventricle 114 through the mitral valve from theleft atrium 118. Blood is pumped from the right ventricle 116, throughthe pulmonary valve into the pulmonary artery. Blood enters the rightventricle 116 from the right atrium 120 through the tricuspid valve. Allparts of the heart 112 and circulatory system 102 are integral to eachother, although they are comprised of various types of tissue.

FIG. 2 illustrates a plot of arterial pressure 200 as a function oftime. The arterial pressure 200 is pulsatile and the waveform generallyrepeats itself each cardiac cycle. The end of the first cardiac cycle202 is approximately 0.8 seconds following the beginning of the cycle.The arterial pressure waveform 200 has a maximum value 204, a minimumvalue 206, and a dicrotic notch 208.

Referring to FIG. 2, typical arterial or systemic pressure within thehuman circulatory system is a time varying value that appears somewhatlike a triangle wave, having rounded peak and minimum curvature, with amaximum value 204 called the peak systolic pressure and the minimumvalue 206 called the minimum diastolic pressure. A small feature in thedownsloping part of the wave is called the dicrotic notch 208 and is thehemodynamic remnant of the closure of the aortic valve.

FIG. 3 illustrates a plot of the right atrial pressure 300 as a functionof time. The right atrial pressure 300 is pulsatile and the waveformgenerally repeats itself each cardiac cycle. The end of the firstcardiac cycle 302 is approximately 0.74 seconds following the beginningof the cycle. The following partial cycle 304 illustrates a right atrialpressure tracing in a patient with an arrhythmia causing the minimumpressure to drop as low as 0 mm Hg.

Referring to FIG. 3, the right atrial pressure has a much lower meanvalue than that in the systemic circulation. The larger, first pressurepulse, within the right atrium, is generated by the contraction of theright atrium which increases pressure within the right atrium. Asmaller, second pressure pulse is generated when the right ventriclecontracts and causes the tricuspid valve to balloon backward into theright atrium. A third pressure pulse is caused by muscular or myocardialcontraction of the heart. A second beat 304 begins at the end 302 of thefirst recorded cycle 300. The second beat 304 is the result of a heartexperiencing electrical disturbances and the beat results in a higherpeak of around 11 or 12 mm Hg and a minimum value of 0 mm Hg.

FIG. 4 illustrates a plot of the left atrial pressure 400 as a functionof time. The left atrial pressure 400 is pulsatile and the waveformgenerally repeats itself each cardiac cycle. The end of the firstcardiac cycle 402 is approximately 0.7 seconds following the beginningof the cycle.

Referring to FIG. 4, the left atrial pressure 400, in the illustratedtracing reaches a maximum of 7.5 mm Hg and a minimum of 5 mm Hg. Theleft atrial pressure 400 pulsatile waveform comprises a larger peak 404followed by a smaller peak 406 during the course of a single cardiaccycle. The first, larger peak 404 is generated by contraction of theleft atrium and the second, smaller peak 406 is generated by contractionof the left ventricle causing retrograde flow into the left atrium andballooning of the mitral valve into the left atrium.

FIG. 5 illustrates a gas block system 500 comprising a core tube 502, anouter shell 504, a proximal hemostasis valve 506, a distal hemostasisvalve 508, a distal connector 510, a reverse flow one way check valve512, a forward flow one way check valve 514, a fluid inlet line 516, afluid outlet line 518, an optional fluid withdrawal pump 520, a liquidreservoir 522, an outer shell lumen 524, and a volume of liquid 526. Thecore tube 502 further comprises a plurality of fenestrations 528. Theouter shell 504 further comprises an outlet port 530 and an inlet port532.

Referring to FIG. 5, the core tube 502 is affixed concentrically withinthe outer shell 504 at both ends. Both ends of the outer shell 504 wherethe core tube 502 penetrates are sealed against the passage of fluidsfrom the outer shell lumen 524. The proximal hemostasis valve 506 isaffixed to the proximal end of the core tube 502 and the central flowlumen of the proximal hemostasis valve 506 is operably connected to thecentral lumen of the core tube 502. The distal hemostasis 508 valve isaffixed to the distal end of the core tube 502 and the central flowlumen of the distal hemostasis valve 508 is operably connected to thecentral lumen of the core tube 502. The distal connector 510 is affixedto the distal end of the distal hemostasis valve 508 and the centralthrough lumen of the distal connector 510 is operably connected to thecentral lumen of the distal hemostasis valve 508. The distal end of thedistal connector 510 is reversibly, or permanently, affixed to theproximal end of a catheter hub (not shown). The reverse flow one waycheck valve 512 is affixed to, and operably connected to, the outletport 530, which is operably connected to the outer shell 504 and thecentral lumen of the reverse flow one way check valve 512 is operablyconnected to the inner lumen 524 of the outer shell 504. The forwardflow one way check valve 514 is affixed to and operably connected to theinlet port 532, which is affixed to and operably connected to the outershell 504. The central lumen of the forward flow one way check valve 514is operably connected to the inner lumen 524 of the outer shell 504. Thefluid inlet line 516 is affixed and operably connected to the centrallumen of the forward flow check valve 514 at one end and affixed to andoperably connected to the liquid reservoir 522 at the other end. Thefluid outlet line 518 is affixed and operably connected to the centrallumen of the reverse flow check valve 512 at one end and affixed to andoperably connected to the optional fluid withdrawal pump 520 or areservoir (not shown) at the other end. The volume of liquid 526 fillsat least a portion of the liquid reservoir 522, the fluid inlet line516, the forward flow check valve 514, and the outer shell 504. In oneembodiment, the fenestrations 528 are integral to the core tube 502 andare generally breaks or holes in the outer wall of the core tube 502.

The outer shell 504 and the core tube 502 can be fabricated from glassor polymers such as, but not limited to, polycarbonate, polysulfone,polypropylene, polyethylene, polyurethane, polyvinyl chloride, acrylic,polystyrene, or the like. The outer shell 504 and the core tube 502 arepreferably fabricated from materials that are transparent and opticallyclear with a minimum of defects or blemishes. The outer shell 504 andthe core tube 502 should be transparent so that bubbles can bevisualized or identified by the user such that they can be removed orguided out of the outer shell 504. Some small amount of colorant isacceptable such that a slight blue, violet, green, or yellow tint ispresent. The outer shell 504 and the core tube 502 can have wallthicknesses that range from 0.020 inches to 0.50 inches, and preferablybetween 0.040 and 0.250 inches. The reverse flow check valve 512 and theforward flow check valve 514, as well as the proximal hemostasis valve506, the distal hemostasis valve 508, and the distal connector 510 canbe fabricated from the same materials as those used for the outer shell504. In addition, the valves 512, 514, 506, and 508 can compriseinternal seals (not shown) fabricated from flexible or elastomericpolymers such as, but not limited to, polyurethane, silicone elastomer,thermoplastic elastomer, latex rubber, or the like. The fluid inlet line516 and the fluid outlet line 518 can be fabricated from materials suchas, but not limited to, polyvinyl chloride, polyurethane, siliconeelastomer, polypropylene, polyethylene, or the like. The fluid reservoir522 can be a bag or a container such as a bottle, box, or tub fabricatedfrom the same materials as the fluid inlet line 516. The gas removalpump 520 can be a syringe that is manually or mechanically operated orit can be a pump such as a roller pump, a diaphragm pump, a centrifugalpump, a piston pump, or the like. The pump 520 can be manually,electrically, or fluidically powered. In another embodiment, the pump520 can be a simple fluid reservoir with no active means of pulling avacuum on the outlet of the reverse flow check valve 512. The pump 520is advantageously oriented higher than the outer shell 504. The outletport 530 and the inlet port 532 can be integral to the outer shell 504or they can be bonded or welded thereto. The outlet port 530 and theinlet port 532 can be perforations in the wall of the outer shell 504.

FIG. 6 illustrates an air block subassembly 600 comprising the core tube502, the outer shell 504, a proximal hemostasis valve 506, the distalhemostasis valve 508, a distal connector 510, the reverse flow one waycheck valve 512, the forward flow one way check valve 514, and an outershell lumen 524. The one way check valves 512 and 514 each furthercomprise an internal connector 602, and an external connector 604.

Referring to FIG. 6, the internal connector 602 is affixed to the outershell 504 and the central lumen of the internal connector is operablyconnected to the central lumen 524 of the outer shell 504 by way ofholes in the outer shell 504. In one embodiment, the external connectors604 are permanently affixed to the outermost edges of the reverse flowcheck valve 512 and the forward flow check valve 514. The internalconnectors 602 and the external connectors 604 can be Luer typeconnectors, or other bayonet mount or screw mount with a tapered sealingport, for example, suitable for attachment to medical fluid lines andconnectors. Referring to FIG. 5, the internal connectors 602 and theexternal connectors 604 can be fabricated from the same materials asthose used to fabricate the outer shell 504.

FIG. 7 illustrates an air block subassembly 600 affixed to a primarycatheter 700. The primary catheter 700 comprises a hub 702, a main tube704, and a hub connector 706. The air block subassembly 600 furthercomprises the proximal hemostasis valve 506, the distal hemostasis valve508, and the distal connector 510.

Referring to FIG. 7, the hub 702 is affixed to the main tube 704. In oneembodiment, the hub 702 has an integral or attached hub connector 706.The hub connector 706 is permanently or releasably affixed to the distalconnector 510 of the air block system 600. The distal connector 510 canbe configured to be a device such as, but not limited to, a luer lock, abayonet mount, a collar with a set screw, an adhesively coupledconnector, a threaded connector, or the like.

FIG. 8 illustrates the air block system 500 affixed to the primarycatheter 700. The primary catheter 700 comprises the hub 702 and themain tube 704. The air block system 500 comprises the outer shell 504,the proximal hemostasis valve 506, the distal hemostasis valve 508, thedistal connector 510, the reverse flow check valve 512, the forward flowcheck valve 514, the liquid inlet line 516, the fluid outlet line 518,the fluid withdrawal pump 520, and the liquid reservoir 522. The airblock system 500 further comprises an air reservoir 802, a power supply804, a plurality of power lines 806, a gas permeable membrane 810, and apower switch 808.

Referring to FIG. 8, the air reservoir 802 is affixed to the end of thefluid outlet line 518 that is opposite the end of the fluid outlet line518 that is connected to the reverse flow one way check valve 512. In anembodiment, the air reservoir 802 can be affixed to the reverse flow oneway check valve 512 directly without the intervening fluid outlet line518. The fluid withdrawal pump 520 is affixed to the air reservoir 802with or without an intervening fluid line (not shown). The power supply804 is operably connected to the fluid withdrawal pump 520 using powerlines 806. In the illustrated embodiment, there are two power lines 806.A power switch 808 can be operably connected to at least one power line806 and used to enable power delivery to the fluid withdrawal pump 520through the power lines 806. In an embodiment, the power supply 804 canbe a battery system and the fluid withdrawal pump 520 can beelectrically powered.

The fluid removal system can be optimized to selectively withdraw onlygasses such as air while leaving liquids behind, within the outer shell504. In an embodiment, a gas permeable membrane 810 can be operablyconnected within or about the outlet line 518. The gas permeablemembrane 810 is a filter comprising, for example, a microporous membranefabricated from materials such as, but not limited to, polypropylene,polyethylene, polytetraflouoroethylene, other polyolefin, polyester, orthe like. The membrane can have porous structures that penetrate fromone side of the membrane to the other. The size of the pores can beabout 100 microns with a range of about 50 microns to about 1000microns. The pore density and pore size can be selected to be compatiblewith a pressure drop across the membrane, as generated by the pump 520or other suction (vacuum) or pressure generating device, so as to removea given volume of air over a reasonable length of time, for example 1-ccin 5 minutes, while preventing the loss of blood or other liquids fromthe system.

FIG. 9 illustrates the air block subassembly 600 comprising the proximalhemostasis valve 506, the distal hemostasis valve 508, and the distalconnector 510 affixed to the primary catheter 700. The air blocksubassembly 600 comprises the perforated core tube 502 which furthercomprises an interior distal surface 910 that is smooth and gentlysloped. A secondary catheter 900 is inserted through the air blocksubassembly 600 and the primary catheter 700. The secondary catheter 900comprises a hub 902 and a main tube 904.

Referring to FIG. 9, the main tube 904 of the secondary catheter 900 isaffixed to the hub 902 and one or more lumens within the main tube 904are operably connected to one or more lumens in the hub 902. The maintube 904 of the secondary catheter 900 is slidably inserted through theproximal hemostasis valve 506, the air block system 600, and the centrallumen of the primary catheter 700. The proximal hemostasis valve 506 andthe distal hemostasis valve 508 operably seal against the passage offluids around the exterior surface of the main tube 904. The innersurfaces of the core tube 502 are smooth and without bumps, especiallyon the distal end 910 of the core tube, so that the secondary catheter900, when inserted in the distal direction, does not hang up or catch onridges, bumps, or ledges. The interior surface of the distal end 910 ofthe core tube 502, when tapering from a larger to a smaller diameterwhen moving in the distal direction, beneficially has a relativelygentle angle of 1 to 45 degrees to facilitate advancement of thesecondary catheter 900, especially if the secondary catheter 900comprises radial enlargements or a curvature or bend at right angles tothe longitudinal axis. Such gentle tapering and lack of bumps or ridgescan also be present on the proximal end of the core tube 502 innersurface, and can reduce friction on a secondary catheter 900 which hasradial enlargements while it is being withdrawn proximally through thecore tube 502.

FIG. 10 illustrates the air block subassembly 600 affixed to the primarycatheter 700 with the main tube 904 of the secondary catheter 900inserted through both the air block subassembly 600 and the primarycatheter 700. The air block subassembly 600 comprises the core tube 502further comprising the plurality of fenestrations 528, the outer shell504, the proximal hemostasis valve 506, the distal hemostasis valve 508,and the distal connector 510. A bolus of air 1000 has escaped into theair block assembly 600 and is being removed from the lumen of the coretube 502, through the fenestrations 528, into the lumen of the outershell 504.

Referring to FIG. 10, an air bubble 1000 is shown trapped within thelumen of the core tube 502. The air bubble 1000 is shown moving upwardtoward the reverse flow check valve 512 due to buoyancy forces generatedby gravity acting on the bubble 1000 and the liquid within the air blocksystem 600. The air bubble 1000 will ultimately move out of the coretube 502 altogether where it will reside within the outer shell 502prior to being withdrawn out through the reverse flow check valve 512and away from the blood path.

FIG. 11 illustrates a side cross-sectional view of a dual chamber airblock 1100. The dual chamber air block 1100 comprises the first outershell 504, the first core tube 502, the distal hemostasis valve 508, theproximal hemostasis valve 506, the reverse flow check valve 512, theforward flow check valve 514, the distal coupler 510, the primarycatheter 700, and the secondary catheter 900 further comprising thesecondary catheter hub 902 and the secondary catheter tube 904. The dualchamber air block 1100 further comprises a second outer shell 1104, asecond core tube 1102, a second reverse flow check valve 1112, and asecond proximal hemostasis valve 1130.

Referring to FIG. 11, the distal end of the second core tube 1102 isaffixed to and its central lumen is operably connected to the proximalend of the proximal hemostasis valve 506. The second proximal hemostasisvalve 1130 is affixed to and its through lumen is operably connected tothe central lumen of the second core tube 1102. The second reverse flowcheck valve 1112 is affixed to the second outer shell 1104 and itscentral lumen operably connected to the internal lumen of the secondouter shell 1104 by way of a fenestration or outlet port in the secondouter shell 1102. A pressurized liquid source is operably connected tothe forward flow check valve 514 or it is directly connected to theinterior volume of the first outer shell 504.

Referring to FIGS. 11 and 5, the sizes of the two chambers of the dualchamber air block 1100 can be approximately the same, or they can varyby as much as 80% in volume. The forward flow check valve 514 can beoperably connected to the pressurized source 522 of liquid 526. Theliquid 526 can be delivered at pressures of between 20 and 300 mm Hg. Itis preferable that the liquid 526 be biologically compatible fluid suchas, but not limited to, ringers solution, isotonic saline, heparinizedsaline, or the like. The liquid 526 can be sterilized and deliveredthrough a sterile system to prevent infection to a patient. The liquid526, delivered at a pressure higher than that of the central venouscirculation, will flow both distally and proximally, if allowed, withinthe first outer shell 504 and the second outer shell 1104. The movementof the liquid 526 is controlled by the distal hemostasis valve 508, theproximal hemostasis valve 506, and the second proximal hemostasis valve1130. Should air be entrained into the second outer shell 1104 throughthe second proximal hemostasis valve 1130, the high pressure within thefirst outer shell 504 will prevent entrance of the air into the firstouter shell through any potential opening or defect in the proximalhemostasis valve 506. A leak or defect in the distal hemostasis valve508 could result in the flow of the liquid 526 through the firstcatheter 700 and into the patient, but since the liquid 526 isbiocompatible, this event will have no adverse clinical effect. Any airthat does become trapped within the system can be drawn out through thereverse flow check valve 512 or the second reverse flow check valve1112. In other embodiments, the forward flow check valve 514 can beeliminated and the line 516 can be directly connected to the outer shell504. In another embodiment, one or more of the reverse flow check valves512 or 1112 can be eliminated and replaced by gas permeable membranes,or simply be connected to the fluid withdrawal line 518.

Referring to FIGS. 5, 6, 7, and 11, the volume of the outer shell 504 or1104 can vary between 0.5 cubic centimeter (cc) and 100-cc. The size ofthe system is beneficially reduced to allow the system 500, 600, or 1100to be connected to a primary catheter 700 and still be maneuveredwithout encumbering the user or hindering manipulation. The air blocksystem 500 is beneficially sterilized prior to use to prevent infectionto a patient.

Referring to FIG. 5, an air block apparatus 500 is disclosed herein,which prevents air from passing through a catheter, cannula, or sheathinto a patient's cardiovascular system, wherein the air block 500comprises an outer shell 500, further comprising a wall and an innerlumen 524 having a proximal end and a distal end, a core tube 502comprising an axially elongate wall, an inner lumen, and a plurality offenestrations 528, wherein the core tube 502 resides within the outershell 504 and is sealed to the outer shell 504 at its proximal end andits distal end, a first hemostasis valve 506 affixed to the core tube502 at the proximal end of the core tube, a second hemostasis valve 508affixed to the core tube 502 at the distal end of the core tube 502, andan outlet port 530 affixed to the wall of the outer shell 504, whereinthe outlet port 530 is operably connected to the inner lumen 524 of theouter shell 504, wherein the fenestrations 528 in the wall of the coretube 502 are large enough to permit air or other gas to pass out of thecore tube 502 and into the inner lumen 524 of the outer shell.

In another embodiment, the air block apparatus can further comprise aninlet port 532 affixed to the wall of the outer shell 504, wherein theinlet port 532 is operably connected to the inner lumen 524 of the outershell 504.

In another embodiment, the air block apparatus can further comprise aninlet port 530 operably connecting the inner lumen 524 of the outershell with a source 522 of liquid 526. The apparatus can also comprise avacuum source 520 operably connected to the outlet port 530, wherein thevacuum source 520 removes gas from the inner lumen 524 of the outershell 504. Referring to FIGS. 5 and 8, the air block apparatus 500 cancomprise a gas permeable membrane 810 operably connected between thevacuum source 520 and the outlet port 530, wherein the gas permeablemembrane 810 permits the removal of gas from the inner lumen 524 of theouter shell 504 while substantially preventing the removal of liquidfrom the inner lumen 524 of the outer shell 504. Referring to FIG. 6,the air block apparatus 500 can also have a core tube 502 that furthercomprises a central bulge 610 extending radially outward such that whenthe inner lumen 524 is oriented perpendicular to the line of gravity,gas moves radially away from the central axis of the core tube 502toward the outer wall, where it is able to pass into the inner lumen ofthe outer shell through fenestrations 528 in the wall of the core tube502.

The core tube 502 of the air block 600 can comprise a central bulge 610extending radially outward, wherein said central bulge 610 is gentlytapered along the inner distal surface 612 of the outer wall of the coretube 502 such that a catheter inserted therethrough, from the proximalend, does not catch, but is guided into the smaller diameter regions ofthe core tube without catching or hanging up as it is advanced distally.In another embodiment, the first, proximal hemostasis valve 506 of theapparatus is configured to receive a catheter and seal around saidcatheter when the catheter is inserted therethrough and further whereinthe proximal hemostasis valve 506 is configured to seal substantiallyagainst the flow or air or liquid when nothing is inserted therethrough.The second hemostasis valve 508 can be configured to receive a catheterand seal around said catheter when the catheter is inserted therethroughand further wherein the distal, or second hemostasis valve 508 isconfigured to seal substantially against the flow or air or liquid whennothing is inserted therethrough. Referring to FIGS. 6 and 7, the airblock apparatus 600 can further comprise an adapter 510 to permitattachment of the distal end of the second hemostasis valve 508 to a hub702 of a catheter 700 such that the central lumen of the core tube 502is operably connected to the inner lumen of the hub 702 of the catheteror sheath 700 as permitted by the second hemostasis valve 508. Theadapter 510 can be configured to permit removable attachment of the airblock apparatus 600 to the hub of the catheter 700.

Referring to FIGS. 5, 6, 7, and 9, in another embodiment, a method ofpreventing substantial infusion of air into the proximal end of a firstcatheter 700 is disclosed, the method comprising the steps of affixingan air block 600 having a longitudinal axis to the proximal end of afirst catheter 700, wherein the air block comprises an outer shell 504,a fenestrated core tube 502, a first hemostasis valve 506, a secondhemostasis valve 508, an inlet port 532, and an outlet port 530,affixing a source 522 of sterile liquid 526 to the inlet port, affixinga gas withdrawal system 520 to the outlet port, inserting a secondarycatheter 900 through the air block into the first catheter or sheath700, wherein the first and second hemostasis valves 506 and 508 preventair from entering or escaping the air block 600, orienting the air block600 such that its longitudinal axis is substantially horizontal relativeto the pull of gravity; and removing gas bubbles that collect betweenthe outer shell 504 and the fenestrated core tube 502 such that the gasbubbles no longer reside within the outer shell 504.

The method can further comprise the step of elevating the source 522 ofsterile liquid 526 above the level of the outer shell 504. The methodcan also comprise the step of activating a pump 520 to remove the gasfrom the outer shell 504 through the outlet port 530. In anotherembodiment, the method can further comprise the step of removing the gasfrom the outer shell 504 through a gas permeable membrane 810 which isoperably connected to the outlet port 530. The method can involvereplacement of the secondary catheter 900 with a guidewire at one ormore points in the procedure. The method can further comprise the stepof collecting the removed gas in a holding chamber 802, which can be aseparate structure or integral to the block 500. In another embodiment,the method can comprise the step of returning any liquid, which wasunintentionally removed from the system, back into the outer shell 504through the inlet port 532.

The method can comprise the step of sterilizing the air block 500 or 600prior to attaching it to the first catheter, sheath, or introducer 700.The method can also comprising the step of packaging the air block 500or 600 within a kit, wherein the kit comprises at least the firstcatheter or sheath 700 and the air block 500, 600. The method cancomprise pre-affixing the air block to the hub 702 of the firstcatheter, sheath, introducer, or cannula 700. The method of can comprisethe step or steps of providing therapeutic intervention within thecardiovascular system wherein the instrumentation is placed through theair block apparatus 500, 600 into the sheath or first catheter 700. Themethod can comprise the step or steps of providing diagnosticintervention within the cardiovascular system through the air blockapparatus 500, 600. The method can comprise routing the first catheteror sheath 700 to the right atrium of the heart through the venoussystem. Subsequent steps can involve passing the first catheter orsheath 700 through the interatrial septum and resides, at its distalend, within the left atrium of the heart.

In another embodiment, an apparatus 1100 is disclosed, which is adaptedfor preventing substantial infusion of air into the proximal end of afirst catheter 700 comprising means for collecting air within a primaryinner chamber 502, means for collecting air within a primary outerchamber 504, means for permitting the air to move from the primary innerchamber 502 to the primary outer chamber 504, means for inserting acatheter 900 through the inner chamber 502, means 506 for preventingsubstantial air from entering the primary inner chamber 502 from theproximal end of the primary inner chamber 502, means 508 for preventingsubstantial air from leaving the primary inner chamber 502 at its distalend while still permitting passage of a catheter 900 therethrough, meansfor infusion of liquid into the primary outer chamber 504, and means forremoval of gas from the primary outer chamber 504. The apparatus 1100can further comprise a secondary, perforated, inner chamber 1102surrounded by a secondary outer chamber 1104, a means 1112 for removingair from the secondary outer chamber 1104, and a secondary proximalhemostasis valve 1130, wherein said secondary, or second, inner andouter chambers 1102 and 1104, respectively, positioned proximally to theprimary inner chamber 502 and operably separated from the primary outerchamber 504 by a means 506 to permit catheter passage between theprimary 502 and secondary 1102 inner chambers while substantiallyprohibiting the flow of fluids between said primary 502 and secondary1102 inner chambers.

An air block apparatus 500, 600, 1100 is disclosed herein, which isadapted for preventing air from passing from a room through a catheter,sheath, cannula, or introducer 700 into a patient's cardiovascularsystem comprising an outer shell 504 comprising a wall and an innerlumen having a proximal end and a distal end, a core tube 502 comprisingan axially elongate wall, an inner lumen, and a plurality offenestrations 528, wherein the core tube 502 resides within the outershell 504 and is sealed to the outer shell 504 at its proximal end andits distal end, a first valve 506 affixed to the inner lumen of the coretube 502 at the proximal end of the core tube 502, wherein said firstvalve 506 permits the passage of a catheter 900 but substantiallyprohibits the flow of fluids, either liquid or room air, therethrough, asecond valve 508 affixed to the inner lumen of the core tube 502 at thedistal end of the core tube 502, wherein said second valve 508 permitsthe passage of a catheter 900 but substantially prohibits the flow offluids, either liquid or room air therethrough, an outlet port 530 forwithdrawing any gas, including room air, collected in the outer shell504, away from the outer shell 504, and a source 522 of sterile,biocompatible liquid 526 delivered at a pressure greater than centralvenous pressure, wherein the source 522 of sterile, biocompatible liquid526 is operably connected to the inner lumen 524 of the outer shell 504,wherein the sterile biocompatible liquid 526 is delivered at a pressurehigher than that of the room air and substantially prevents the flow ofroom air from the first valve 506 into the inner lumen of the core tube502.

An air block apparatus 500, 600, 1100 is disclosed, which is adapted forpreventing gas from passing from a room environment through a catheter700 into a patient's cardiovascular system comprising a chamber 504affixed to the proximal end of a first catheter 700, wherein the chamber504 is operably connected to a source 522 of liquid 526 which ispressurized to a level above that of the pressure within thecardiovascular system, a first valve 506 affixed to the proximal end ofthe chamber 504, wherein said first valve 506 permits insertion of asecond catheter 900 from a room environment through the first valve 506and into the chamber 504, and a second valve 508 affixed to the distalend of the chamber 504, wherein said second valve 508 permits insertionof the second catheter 900 from the chamber 504, through the secondvalve 508, into the proximal end the first catheter 700, wherein thefirst valve 506 and the second valve 508 are configured to permitcatheter 900 passage but substantially prohibit the passage of air, fromthe room environment, therethrough.

In one embodiment, the cross-sectional area of the outer shell 504 issubstantially larger than the cross-sectional area of the catheter 700.In one embodiment, the cross-sectional area of the outer shell 504 is atleast three times greater than the cross-sectional area of the catheter700. In yet other embodiments, the cross-sectional area of the outershell 504 is at least two times greater than the cross-sectional area ofthe catheter 700.

In another embodiment, the diameter of the outer shell 504 issubstantially larger than the diameter of the catheter 700. In oneembodiment, the diameter of the outer shell 504 is at least three timesgreater than the diameter area of the catheter 700. In yet otherembodiments, the diameter of the outer shell 504 is at least two timesgreater than the diameter of the catheter 700.

FIG. 12 illustrates an air embolism prevention device, or air block1200, comprising a shell 1202, an exit valve 1204, an intravascularsheath 1206, and a catheter insert port 1208. The air embolismprevention device 1200 prevents air bubbles from entering theintravascular sheath 1206 during any heart procedure, left-sided orright-sided. Air bubbles that get introduced into the vasculature couldcause stroke, myocardial infarct, or other ischemic event. The shell1202 is affixed to the intravascular sheath 1206 by a coupler (notshown) or it is permanently attached by bonding, welding, or the like.The catheter insert port 1208 is affixed to the proximal end of theshell 1202. The exit valve 1204 is affixed to the distal end of theshell 1202 and is coupled, at or near its distal end, to a pointsubstantially near the proximal end of the intravascular sheath 1206.The exit valve 1204 is operably connects the through lumen of theintravascular sheath 1206 to the internal volume of the shell 1202 undercontrol of the valving mechanism within the exit valve 1204. The insertport 1208 operably connects the external environment with the interiorvolume of the shell 1202.

FIG. 13 illustrates a system and method of preventing air embolismduring vascular procedures. The system, an air block or trap 1250,comprises a case 1252, a perforated cylindrical track 1254 furthercomprising fenestrations or perforations 1270, an inlet valve 1256, anoutlet valve 1258, an infusion port 1260 for a volume of pressurizedliquid 1262, an air escape valve 1264, the volume of liquid 1262, avolume of collected air 1266, and a medical introducer sheath 1268. Theperforated cylindrical track 1254 allows catheter (not shown) passageand guide catheter (not shown) use when guidewires (not shown) have beenintroduced through the medical introducer sheath 1268. The perforatedcylindrical track 1254 further allows any air collected 1266 within itslumen to escape through the perforations 1270 into the surroundingchamber defined by annulus between the shell or case 1252 and theperforated cylindrical track 1254. The pressurized infusion port 1260prevents bleed out and air entry, maintaining a fluid (saline) interfaceat all times when the medical introducer sheath 1268 is used. The entireair block 1250 can be attached or affixed to a medical introducer sheath1268, catheter, cannula, or the like by way of a coupler (not shown)which engages, either permanently or removably, at or near the proximalend of the sheath 1268 hub (not shown). The inlet valve 1256 and theoutlet valve 1258 are preferably hemostasis type valves, such as thoseknown in the art of medical devices.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. For example, the gas withdrawal system can bepowered by an external power source or it can be powered manually. Thescope of the invention is therefore indicated by the appended claimsrather than the foregoing description. All changes that come within themeaning and range of equivalency of the claims are to be embraced withintheir scope.

1. An air block apparatus adapted for preventing gas from passingthrough a catheter into a patient's cardiovascular system comprising: anouter shell comprising a wall and an inner lumen having a proximal endand a distal end; a core tube comprising an axially elongate wall, aninner lumen, and a plurality of fenestrations, wherein the core tuberesides within the outer shell; a first hemostasis valve affixed to theinner lumen of the core tube towards the proximal end of the core tube;a second hemostasis valve affixed to the inner lumen of the core tubetowards the distal end of the core tube; and an outlet port affixed tothe wall of the outer shell, wherein the outlet port is operablyconnected to the inner lumen of the outer shell; wherein thefenestrations in the wall of the core tube are large enough to permitgas to pass out of the core tube and into the lumen of the outer shell.2. The apparatus of claim 1 further comprising an inlet port affixed tothe wall of the outer shell, wherein the inlet port is operablyconnected to the inner lumen of the outer shell.
 3. The apparatus ofclaim 1 further comprising an inlet port operably connecting the innerlumen of the outer shell with a source of liquid.
 4. The apparatus ofclaim 1 further comprising a vacuum source operably connected to theoutlet port, wherein the vacuum source removes gas from the inner lumenof the outer shell.
 5. The apparatus of claim 1 further comprising a gaspermeable membrane operably connected between the vacuum source and theoutlet port, wherein the gas permeable membrane permits the removal ofgas from the inner lumen of the outer shell while substantiallypreventing the removal of liquid from the inner lumen of the outershell.
 6. The apparatus of claim 1 wherein the core tube furthercomprises a central bulge extending radially outward such that when theinner lumen is oriented perpendicular to the line of gravity, gas movesaway from the central axis of the core tube toward the outer wall, whereit is able to pass into the inner lumen of the outer shell throughfenestrations in the wall of the core tube.
 7. The apparatus of claim 1wherein the core tube comprises a central bulge extending radiallyoutward and further wherein said central bulge is gently tapered alongthe inner surface of the outer wall of the core tube such that acatheter inserted therethrough, from the proximal end, does not catch,but is guided into the smaller diameter regions of the core tube withoutcatching or hanging up as it is advanced distally.
 8. The apparatus ofclaim 1 wherein the first hemostasis valve is configured to receive acatheter and seal around said catheter when the catheter is insertedtherethrough and further wherein the proximal hemostasis valve isconfigured to seal substantially against the flow or air or liquid whennothing is inserted therethrough.
 9. The apparatus of claim 1 whereinthe second hemostasis valve is configured to receive a catheter and sealaround said catheter when the catheter is inserted therethrough andfurther wherein the proximal hemostasis valve is configured to sealsubstantially against the flow or air or liquid when nothing is insertedtherethrough.
 10. The apparatus of claim 1 further comprising an adapterto permit attachment of the distal end of the second hemostasis valve toa hub of a catheter such that the central lumen of the core tube isoperably connected to the inner lumen of the hub of the catheter aspermitted b the second hemostasis valve.
 11. The apparatus of claim 10wherein the adapter permits removable attachment of the air blockapparatus to the hub of the catheter.
 12. A method of preventingsubstantial infusion of air into the proximal end of a first cathetercomprising: affixing an air block having a longitudinal axis to theproximal end of a first catheter, wherein the air block comprises anouter shell, a fenestrated core tube, a first hemostasis valve, a secondhemostasis valve, an inlet port, and an outlet port; affixing a sourceof sterile liquid to the inlet port; affixing a gas withdrawal system tothe outlet port; inserting a secondary catheter through the air blockinto the first catheter, wherein the first and second hemostasis valvesprevent air from entering or escaping the air block; orienting the airblock such that its longitudinal axis is substantially horizontalrelative to the pull of gravity; and removing gas bubbles that collectbetween the outer shell and the fenestrated core tube such that the gasbubbles no longer reside within the outer shell.
 13. The method of claim12 further comprising the step of elevating the source of sterile liquidabove the level of the outer shell.
 14. The method of claim 12 furthercomprising the step of activating a pump to remove the gas from theouter shell through the outlet port.
 15. The method of claim 12 furthercomprising the step of removing the gas from the outer shell through agas permeable membrane which is operably connected to the outlet port.16. The method of claim 12 wherein the secondary catheter is aguidewire.
 17. The method of claim 12 further comprising the step ofcollecting the removed gas in a holding chamber.
 18. The method of claim12 further comprising the step of returning any liquid, which wasunintentionally removed from the system, back into the outer shellthrough the inlet port.
 19. The method of claim 12 further comprisingthe step of sterilizing the air block prior to attaching it to the firstcatheter.
 20. The method of claim 12 further comprising the step ofpackaging the air block within a kit, wherein the kit comprises at leastthe first catheter and the air block.
 21. The method of claim 12 whereinthe air block is pre-affixed to the hub of the first catheter.
 22. Themethod of claim 12 further comprising the step of providing therapeuticintervention within the cardiovascular system.
 23. The method of claim12 further comprising the step of providing diagnostic interventionwithin the cardiovascular system.
 24. The method of claim 12 wherein thefirst catheter is routed to the right atrium of the heart through thevenous system, passes through the interatrial septum and resides, at itsdistal end, within the left atrium of the heart.
 25. An apparatusadapted for preventing substantial infusion of air into the proximal endof a first catheter comprising: means for collecting air within aprimary inner chamber; means for collecting air within a primary outerchamber; means for permitting the air to move from the inner chamber tothe outer chamber; means for inserting a catheter through the innerchamber; means for preventing substantial air from entering the innerchamber from the proximal end of the inner chamber; means for preventingsubstantial air from leaving the inner chamber at its distal end whilestill permitting passage of a catheter therethrough; means for infusionof liquid into the outer chamber; and means for removal of gas from theouter chamber.
 26. The apparatus of claim 25 further comprising asecond, perforated, inner chamber surrounded by a second outer chamber,a means for removing air from the second outer chamber, and a secondproximal hemostasis valve, wherein said second inner and outer chamberspositioned proximally to the primary inner chamber and operablyseparated from the primary outer chamber by a means to permit catheterpassage between the primary and secondary inner chambers whilesubstantially prohibiting the flow of fluids between said primary andsecondary inner chambers.
 27. An air block apparatus adapted forpreventing air from passing from a room through a catheter into apatient's cardiovascular system comprising: an outer shell comprising awall and an inner lumen having a proximal end and a distal end; a coretube comprising an axially elongate wall, an inner lumen, and aplurality of fenestrations, wherein the core tube resides within theouter shell and is sealed to the outer shell towards its proximal endand its distal end; a first valve affixed to the inner lumen of the coretube towards the proximal end of the core tube, wherein said first valvepermits the passage of a catheter but substantially prohibits the flowof fluids, either liquid or room air, therethrough; a second valveaffixed to the inner lumen of the core tube towards the distal end ofthe core tube, wherein said second valve permits the passage of acatheter but substantially prohibits the flow of fluids, either liquidor room air therethrough; an outlet port for withdrawing any gas,including room air, collected in the outer shell, away from the outershell; and a source of sterile, biocompatible liquid delivered at apressure greater than central venous pressure, wherein the source ofsterile, biocompatible liquid is operably connected to the inner lumenof the outer shell; wherein the sterile biocompatible liquid isdelivered at a pressure higher than that of the room air andsubstantially prevents the flow of room air from the first valve intothe inner lumen of the core tube.
 28. An air block apparatus adapted forpreventing gas from passing from a room environment through a catheterinto a patient's cardiovascular system comprising: a chamber affixedtowards the proximal end of a first catheter, wherein the chamber isoperably connected to a source of liquid which is pressurized to a levelabove that of the pressure within the cardiovascular system; a firstvalve affixed towards the proximal end of the chamber, wherein saidfirst valve permits insertion of a second catheter from a roomenvironment through the first valve and into the chamber; and a secondvalve affixed towards the distal end of the chamber, wherein said secondvalve permits insertion of the second catheter from the chamber, throughthe second valve, into the proximal end the first catheter; wherein thefirst valve and the second valve are configured to permit catheterpassage but substantially prohibit the passage of air, from the roomenvironment, therethrough.
 29. An air block apparatus comprising: anouter shell comprising a wall and an inner lumen having a proximal endand a distal end; and a core tube dimensioned to allow a device to passthrough the core tube, the core tube comprising an axially elongatewall, an inner lumen, and a plurality of fenestrations, wherein the coretube resides within the outer shell and is connected to the outer shelltowards its proximal end and towards its distal end wherein thefenestrations in the wall of the core tube are large enough to permitgas to pass out of the core tube and into the lumen of the outer shell.30. An air block apparatus adapted for preventing gas from passingthrough a catheter into a patient's cardiovascular system comprising: anouter shell comprising a wall and an inner lumen having a proximal endand a distal end, the outer shell dimensioned to allow a catheter topass through the outer shell wherein the interior dimensions of theouter shell are substantially greater than the outside dimension of thecatheter; and a pressurized liquid within the outer shell external tothe catheter to inhibit gas from entering a patient's cardiovascularsystem.
 31. The apparatus of claim 28 wherein the cross-sectional areaof the outer shell is at least three times greater than thecross-sectional area of the catheter.
 32. The apparatus of claim 28further comprising a first hemostasis valve affixed towards the proximalend of the outer shell.
 33. The apparatus of claim 30 further comprisinga second hemostasis valve affixed towards the distal end of the outershell.